1. Field of the Invention
The present invention relates to programmable integrated circuit devices, and more particularly to a method and apparatus for hot-electron channel altering the characteristics of an integrated circuit by means of programmable circuits.
2. Background Art
At present, integrated circuits are altered by making discretionary connections using either fusible links or antifusible links, wherein a fusible link is one that provides a closed connection when first formed and an antifusible link is one that provides an open connection when first formed.
Typical examples of fuse technology are described in U.S. Pat. No. 5,345,110 issued Sep. 6, 1994 to Renfro et al., U.S. Pat. No. 5,581,505 issued Dec. 3, 1996 to Lee.
Other techniques for altering integrated circuits are described in U.S. Pat. No. 5,517,634 issued May 14, 1996 to Ehrlich that discloses modifying the threshold characteristics of pass transistors with hot electrons, U.S. Pat. No. 5,018,102 issued May 21, 1991 to Houston that discloses the use of capacitors to force a CMOS memory cell to assume a desired logic state when power is applied to the device, and U.S. Pat. No. 4,852,063 issued Jul. 25, 1989 to McNutt discloses a technique wherein an avalanche voltage is used to program a nonvolatile memory.
A publication entitled "Programmable Compare Circuit` by K. E. Beilstein and R. A. Lipa in RESEARCH DISCLOSURE, August 1987, Number 280 by Kenneth Mason Publications Ltd, England discloses a technique wherein a hot electron threshold shift is used to program a compare circuit which can be used to eliminate the need for laser fuse blowing to access redundant circuits.